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Circadian and Homeostatic Regulation of Structural Synaptic Plasticity in Hypocretin Neurons NEURON Appelbaum, L., Wang, G., Yokogawa, T., Skariah, G. M., Smith, S. J., Mourrain, P., Mignot, E. 2010; 68 (1): 87-98

Abstract

Neurons exhibit rhythmic activity that ultimately affects behavior such as sleep. In living zebrafish larvae, we used time-lapse two-photon imaging of the presynaptic marker synaptophysin in hypocretin/orexin (HCRT) neurons to determine the dynamics of synaptic modifications during the day and night. We observed circadian rhythmicity in synapse number in HCRT axons. This rhythm is regulated primarily by the circadian clock but is also affected by sleep deprivation. Furthermore, NPTX2, a protein implicated in AMPA receptor clustering, modulates circadian synaptic changes. In zebrafish, nptx2b is a rhythmic gene that is mostly expressed in hypothalamic and pineal gland cells. Arrhythmic transgenic nptx2b overexpression (hcrt:NPTX2b) increases synapse number and abolishes rhythmicity in HCRT axons. Finally, hcrt:NPTX2b fish are resistant to the sleep-promoting effects of melatonin. This behavioral effect is consistent with NPTX2b-mediated increased activity of HCRT circuitry. These data provide real-time in vivo evidence of circadian and homeostatic regulation of structural synaptic plasticity.

View details for DOI 10.1016/j.neuron.2010.09.006

View details for Web of Science ID 000283704200010

View details for PubMedID 20920793

View details for PubMedCentralID PMC2969179